A kinetic study on the reductive opening of the diphenylmethylene acetal in methyl 2,3-O-diphenylmethylene-α-L-rhamnopyranoside.

Reductive opening of the diphenylmethyl acetal in methyl 2,3-O-diphenylmethylene-α-l-rhamnopyranoside has been investigated by kinetic studies, and the results have been compared to those recently obtained by quantum chemical calculations. In contrast to the previous theoretical calculations which related only to the presumably rate limiting step of the reductive opening, the reaction system LiAlH(4), AlCl(3), and the title compound consists of at least four simultaneous reactions. Nevertheless, reasonable agreement can be found between the activation Gibbs free energy obtained from kinetic measurements and the theoretically calculated ones in spite of the experimental errors and the approximate nature of theoretical calculations.

In vitro FT-IR study of the effects of hydrogen peroxide on superficial tooth enamel.

Objectives: The aim of the present study was to determine the alteration in human enamel after hydrogen peroxide treatment using FT-IR spectroscopy. It is hypothesized that infrared spectroscopy is capable of showing alterations in human enamel after peroxide treatment and the alteration in enamel is proportional to peroxide concentration.

Methods: The effects of 10, 20 and 30% hydrogen peroxide solutions on human enamel were tested.